Medical experts have discovered that up to 30 per cent of people who fall seriously ill with the new coronavirus disease Covid-19 are developing potentially deadly blood clots.

Doctors say the clots, known as thrombosis, could be contributing to the number of people dying of the disease.

The blood is clotting because of inflammation in the lungs caused by the body's reaction to the virus, reports the BBC.

Doctors around the world started seeing a far higher rate of blood clots in new patients in March and scans have shown hundreds of micro-clots in patients' lungs.

There has also been an increase in Deep Vein Thrombosis (DVT).

Clots like this become deadly when pieces break off, travel through the body and block blood vessels.

Roopen Arya, professor of thrombosis and haemostasis at King's College Hospital, London, said: "Some of the more recent studies show that nearly half the patients have pulmonary embolism or blood clot on the lungs."

Scientists at the hospital say coronavirus can make the blood much more 'sticky'.

Thrombosis expert Prof Beverley Hunt told the BBC sticky blood is leading to higher rates of strokes and heart attacks - some fatal.

The blood thinners being used to treat the clots are not always working - and using too much can be fatal in itself.